Air Quality Particulate Matter

import matplotlib.pyplot as plt
import numpy as np

np.random.seed(42)

# Air quality data
cities = ['Tokyo', 'New York', 'London', 'Paris', 'Sydney', 'Singapore']
pm25 = np.array([15.2, 12.8, 11.5, 14.2, 8.5, 18.5])
pm10 = np.array([28.5, 22.4, 18.8, 25.6, 15.2, 32.4])
pm25_err = np.array([2.5, 2.2, 1.8, 2.4, 1.5, 3.2])
pm10_err = np.array([4.2, 3.5, 3.0, 4.0, 2.5, 5.0])

fig, ax = plt.subplots(figsize=(10, 6), facecolor='#ffffff')
ax.set_facecolor('#ffffff')

x = np.arange(len(cities))
width = 0.35

bars1 = ax.bar(x - width/2, pm25, width, yerr=pm25_err, label='PM2.5',
               color='#4927F5', edgecolor='#1f2937', capsize=4,
               error_kw={'ecolor': '#374151', 'elinewidth': 1.5})
bars2 = ax.bar(x + width/2, pm10, width, yerr=pm10_err, label='PM10',
               color='#27D3F5', edgecolor='#1f2937', capsize=4,
               error_kw={'ecolor': '#374151', 'elinewidth': 1.5})

# WHO guidelines
ax.axhline(y=15, color='#F5276C', linestyle='--', linewidth=1.5, 
           label='WHO PM2.5 Limit', alpha=0.7)
ax.axhline(y=45, color='#F5B027', linestyle=':', linewidth=1.5, 
           label='WHO PM10 Limit', alpha=0.7)

ax.set_xlabel('City', fontsize=11, color='#374151', fontweight='500')
ax.set_ylabel('Concentration (μg/m³)', fontsize=11, color='#374151', fontweight='500')
ax.set_title('Air Quality: Particulate Matter by City', fontsize=14, 
             color='#1f2937', fontweight='bold', pad=15)

ax.set_xticks(x)
ax.set_xticklabels(cities)
ax.legend(facecolor='#f8fafc', edgecolor='#d1d5db', fontsize=9, loc='upper right')
ax.tick_params(colors='#6b7280', labelsize=9)
ax.set_ylim(0, 50)
ax.grid(True, axis='y', alpha=0.3, color='#d1d5db')
for spine in ax.spines.values():
    spine.set_color('#d1d5db')

plt.tight_layout()
plt.show()